助动词“can”的过去式; 能够，打算; 用于假设语气的条件句; 用于虚拟语气的结论句

动词

1. I would go if I could.
能去我就去。

2. You could have been more considerate.
你本来可以更慎重些。

3. Could you do sth. for me?
你能替我做件事情吗？

4. I could run faster then.
我那时能跑得更快一些。

5. Couldn't you try it again?
你可否再试一下？

传递信息

A：Could you give him this (message/ report/ document), please?
你可以把这个（口讯/报告/文件）给他吗？

B：No problem.
没问题。

还礼

A：You’ve been a big help.
你帮我大忙了。

B：I’m glad I could help.
能帮助您，我非常高兴。

请求帮助

A：Could you hand me the salt, please?
您能把盐递过来吗?

B：With pleasure. Here you are.
乐意为您效劳。